Azionamenti elettricicon motori sincroni
per trazione
Nicola Bianchi
Department of Industrial EngineeringUniversity of Padova
35131 Padova (ITALY)[email protected]
LE PROSPETTIVE DELLA TRAZIONEFERROVIARIA PER GLI ANNI 2020 - 2030
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Outline
1 Synchronous Permanent Magnet Motor
2 Synchronous Reluctance Motor
3 The PM assistance
4 Synchronous IPM Motor
5 Conclusions
N. Bianchi Synchronous Motor Drives for traction applications 2
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
SynchronousPermanent Magnet (PM)
Motor
N. Bianchi Synchronous Motor Drives for traction applications 3
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The synchronous SPM motorhigh torque density,high efficiency,high dynamics.
N. Bianchi Synchronous Motor Drives for traction applications 4
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Rare earth PMHigh magnetic energy and high coercive force.
−2000 −1500 −1000 −500 0−2
−1.5
−1
−0.5
0
0.5
1
1.5
Magnetic field (kA/m)
Flu
x d
en
sity
(T
)
20°C140°C sintered
NdFeBN45UH
Ferrite C12
N. Bianchi Synchronous Motor Drives for traction applications 5
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Surface Mounted PM motorThe PMs are mounted on the rotor surface
N. Bianchi Synchronous Motor Drives for traction applications 6
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Stator and rotor
N. Bianchi Synchronous Motor Drives for traction applications 7
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
PM glueing and rotor bandage
N. Bianchi Synchronous Motor Drives for traction applications 8
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Rotor bandage
for high speed applications
N. Bianchi Synchronous Motor Drives for traction applications 9
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Non-overlapped coil toothto reduce the end-winding length (weight and cost).
N. Bianchi Synchronous Motor Drives for traction applications 10
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Vector diagramLow leakage inductance Lσ.High power factor cosϕ.Only torque current Iq (no magnetizing current Id ).Lower Joule losses and high efficiency.
d axis
q axis
ie
ve
I
Vφ
Λpmj- IqLσ
IqLj σΛpm
Iq=j
=90°
N. Bianchi Synchronous Motor Drives for traction applications 11
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Howeverthere are also some drawbacks.
N. Bianchi Synchronous Motor Drives for traction applications 12
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Rotor lossesdue to current time harmonics and MMF space harmonics.
N. Bianchi Synchronous Motor Drives for traction applications 13
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Limited flux-weakening operations
No capability of constant-power versus speed operationThis implies an oversize of the inverter VA rating.
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
SynchronousReluctance
Motor
N. Bianchi Synchronous Motor Drives for traction applications 15
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The synchronous reluctance (REL) motoris attractive thanks to its
absence of rare-heart permanent magnet,high torque density,fault–tolerant capability.
N. Bianchi Synchronous Motor Drives for traction applications 16
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
In REL machine:a high permeability path.It is referred to as the direct–axis path.
d
q
N. Bianchi Synchronous Motor Drives for traction applications 17
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
In REL machine: two different rotor paths for the fluxa low permeability path.It is referred to as the quadrature–axis path.
d
q
N. Bianchi Synchronous Motor Drives for traction applications 18
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
REL motorThe higher flux linkage along d–axis.
The q–axis flux linkage is limited by the rotor flux barriers.
−6 −4 −2 0 2 4 6−0.8
−0.6
−0.4
−0.2
0
0.2
0.4
0.6
0.8
Corrente assorbita [Apk]
Flussiconcatenati[Vs]
flusso di asse−qflusso di asse−d
N. Bianchi Synchronous Motor Drives for traction applications 19
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The flux linkages can be expressed as
λd = Ld idλq = Lq iq
The rotor saliency is defined asthe ratio between the d– and q–axis inductance:
ξ =Ld
Lq
Average torque
τdq =32
p(Ld − Lq)iq id
N. Bianchi Synchronous Motor Drives for traction applications 20
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The REL motor is current controlledId current is the “magnetizing” currentIq current is the “torque” current
d axis
q axis
Id
LdId
Iq
ie
ve
IV
φ
LdIdj
IqLqj
- IqLq
they are combined to get the maximum torque density.N. Bianchi Synchronous Motor Drives for traction applications 21
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Torque map in the Id–Iq plane
Constant torque curve as a function of Id and Iq
0
0.5
1.0
1.5
2.0
0 0.5 1.0 1.5 2.0
q-ax
is c
urre
nt
d-axis current
Motor torque
max TI
(p.u.)
(p.u
.)(p.u.)
0.25
0.5
0.75
1.0
1.25
1.5
1.75
2.0
N. Bianchi Synchronous Motor Drives for traction applications 22
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
A drawback: the quite low power factor.The voltage vector leads the current vectorof a quite large angle ϕ.
d axis
q axis
Id
LdId
Iq
ie
ve
IV
φ
LdIdj
IqLqj
- IqLq
The volt-ampere ratings of the inverteris 30 to 40 % higher than mechanical output power.
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Test benchfor measuring torque vs current angle and torque ripple.
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Experimental resultsAverage torque versus current angle of REL motor.Currents used in the tests are 5 A, 10 A, 15 A and 20 A
non-skewedrotor
skewed rotor
N. Bianchi Synchronous Motor Drives for traction applications 25
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
REL motor: torque and power versus speedExperimental versus simulated results.
N. Bianchi Synchronous Motor Drives for traction applications 26
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Mechanical stress on rotor bridges
Rotor iron bridgesare designed so asto sustain bothmagnetic andcentrifugal forces.
N. Bianchi Synchronous Motor Drives for traction applications 27
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The PM assistance
N. Bianchi Synchronous Motor Drives for traction applications 28
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
PM assisted synchronous reluctance (PMAREL) machineA PM can be inset in the rotor flux–barriers.The aim:
to saturate the rotor iron bridges,to increase the motor torque,to increase the power factor.
N. Bianchi Synchronous Motor Drives for traction applications 29
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Rectangular holes have to be considered so asto inset the PM within the rotor flux–barriers
Insertion of the assisting PMs into rotor flux–barriers
N. Bianchi Synchronous Motor Drives for traction applications 30
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
a part of the PM flux tends to saturate the iron bridgesThis implies:
an increase of the torque andan increase of the power factor.
Part of the PM flux flows into the iron bridges.
N. Bianchi Synchronous Motor Drives for traction applications 31
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
There are advantages in adopting PMs.The PM added along the negative q–axiscompensates the flux linkage LqIq.
d axis
q axis
IdLdId
Iq
ie
ve
I
V
φ
LdIdj- IqLq
mj
IqLqj
m-j
Vector diagram of PMAREL motor.
N. Bianchi Synchronous Motor Drives for traction applications 32
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The advantage is twofold.1 An increase of the power factor.
Thus, a PMAREL motor requires lower Volt-Ampererating for given nominal mechanical power.
2 The electromagnetic torque of the motor increases.
A PM torque term is added to the reluctance torqueterm.
N. Bianchi Synchronous Motor Drives for traction applications 33
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Air–gap flux density distribution
0 100 200 300 400 500 600 700−0.2
−0.1
0
0.1
0.2
Bn
(T)
The added PM is minimumto maintain the intrinsic fault–tolerant capability.
the back EMF is low,the short–circuit current is lowthe corresponding braking torque is low.
N. Bianchi Synchronous Motor Drives for traction applications 34
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
PMAREL motor: torque and power versus speedExperimental versus simulated results.
N. Bianchi Synchronous Motor Drives for traction applications 35
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Drawbackthere is a high torque ripple, if not correctly designed.
Remedial strategies1 rotor skewing (step–skewing);2 suitable choice of the number of flux–barriers,3 shifting of the flux–barriers;4 asymmetry of the flux–barrier geometry.
N. Bianchi Synchronous Motor Drives for traction applications 36
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
REL motor — Skewing effect on torque ripplemeasured torque versus mechanical position I = 10 A
0 90 180 270 360
11
12
13
Torq
ue[N
m]
θm
[degrees]
non skewed rotor
0 90 180 270 360
11
12
13
Torq
ue[N
m]
θm
[degrees]
skewed rotor
N. Bianchi Synchronous Motor Drives for traction applications 37
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
REL motor — Skewing effect on torque ripplemeasured torque versus mechanical position I = 20 A
0 90 180 270 36022
24
26
28
Torq
ue[N
m]
θm
[degrees]
non skewed rotor
0 90 180 270 36022
24
26
28
Torq
ue[N
m]
θm
[degrees]
skewed rotorN. Bianchi Synchronous Motor Drives for traction applications 38
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Photos of the "Romeo and Juliet" laminations
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Photo of the "Machaon" lamination
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Measured torque comparisonsymmetric PMAREL motor
0 90 180 270 3602
2.1
2.2
2.3
Angular position (mechanical degrees)
Tor
que
(N
m)
"Romeo and Juliet" motor
0 90 180 270 3601.8
1.9
2
2.1
Angular position (mechanical degrees)
Tor
que
(N
m)
"Machaon" motor
0 90 180 270 3602
2.1
2.2
2.3
Angular position (mechanical degrees)
Tor
que
(N
m)
The resulting torque ripple is about one third.N. Bianchi Synchronous Motor Drives for traction applications 41
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
SynchronousInterior Permanent Magnet (IPM)
Motor
N. Bianchi Synchronous Motor Drives for traction applications 42
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The PM within the flux barrier is a rare earth PM.Interior PM (IPM) machine.The aim is
the increase of the motor torque,the improvement of the torque vs speed characteristic.
N. Bianchi Synchronous Motor Drives for traction applications 43
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
An IPM motor for an electric scooterStandard stator.Two flux–barriers per pole in the rotor.
N. Bianchi Synchronous Motor Drives for traction applications 44
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
A 12–slot 10–pole prototype with non–overlapped coilsand two flux–barriers per pole in the rotor.
N. Bianchi Synchronous Motor Drives for traction applications 45
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Picture of the rotor lamination
In fractional-slot winding machinesthe reluctance torque component is reduced
The dominant torque component is due to the PM flux.
N. Bianchi Synchronous Motor Drives for traction applications 46
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Picture of the rotor laminationIPM motor lamination for naval propulsion system
N. Bianchi Synchronous Motor Drives for traction applications 47
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Fractional–slot winding with non–overlapped coilsallows a physical separation between the phases.
A dual–three phase fractional–slot IPM machineis characterized by two identical windings,each supplied by a separate inverter.
N. Bianchi Synchronous Motor Drives for traction applications 48
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
To achieve a smooth torque is a challengein fractional–slot machine with anisotropic rotor.
2
1
3
45
6
7
8
9
10 11
12
2
1
3
45
6
7
8
9
10 11
12
Two-layer winding Four-layer winding
It is also possible to optimize the windingadjusting the number of conductors of the coilsso that specific harmonics can be canceled.
N. Bianchi Synchronous Motor Drives for traction applications 49
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
The torque ripple results to be always lower than 5%,regardless to the adopted trajectory.
N. Bianchi Synchronous Motor Drives for traction applications 50
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Conclusions
N. Bianchi Synchronous Motor Drives for traction applications 51
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Synchronous SPM motor:Advantages:
high torque density,high efficiency
Drawbacks:expensive PMs,no suitable for Flux-weakening.
N. Bianchi Synchronous Motor Drives for traction applications 52
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Synchronous REL motor:Advantages:
robust and cheap structure,fault-tolerant,
Drawbacks:low Power Factor,mechanical limit at very high speed.
N. Bianchi Synchronous Motor Drives for traction applications 53
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Synchronous IPM and PM–assisted REL motor:Advantages:
a Power Factor improvement,good Flux–Weakening capability,
Drawbacks:limited overload,high torque ripple.
N. Bianchi Synchronous Motor Drives for traction applications 54
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
Thank youfor your attention
Department of IndustrialEngineering
University of Padova — Italy
N. Bianchi Synchronous Motor Drives for traction applications 55
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
N. Bianchi.Electrical Machine Analysis using Finite Elements.Power Electronics and Applications Series. CRC Press, Taylor & Francis Group, Boca Raton, FL, USA,2005.
N. Bianchi. Analysis of the IPM motor – Part I, Analytical approach, in ”Design, Analysis, and Controlof Interior PM Synchronous Machines“ (N. Bianchi, T.M. Jahns editors),IEEE IAS Tutorial Course notes, IAS Annual Meeting, CLEUP, Seattle, October 3, 2005, chapter 3,pages 3.1–3.33 ([email protected]).
N. Bianchi, M. Dai Pré, and S.Bolognani."Design of a fault–tolerant ipm motor for electric power steering."Proc. of IEEE Power Electronics Specialist Conference, PESC’05, 12–16 June 2005.
N. Bianchi, S. Bolognani, Ji-Hoon Jang, and Seung-Ki Sul.“Comparison of PM motor structures and sensorless control techniques for zero-speed rotor positiondetection.”IEEE Trans. on PE, vol.22, no.6, pp. 2466 –2475, Nov. 2007.
N. Bianchi and S. Bolognani."Reducing torque ripple in pm synchronous motors by pole shifting."Proceedings of International Conference on Electrical Machines, ICEM, Aug. Helsinki, 2000.
N. Bianchi, S. Bolognani, D. Bon, and M. Dai Pré,"Rotor flux-barrier design for torque ripple reduction in synchronous reluctance and pm-assistedsynchronous reluctance motors,"IEEE Transactions on Industry Applications, vol. 45, no. 3, pp. 921 –928, May-June 2009.
M. Barcaro and N. Bianchi.“Interior PM Machines using Ferrite to Substitute RareâEarth Surface PM Machines.”Conf. Rec. of Int. Conf. of Electr. Machines, ICEM, Marsille (F), pp. 1–7, June 2012.
N. Bianchi Synchronous Motor Drives for traction applications 56
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SynchronousPermanentMagnet Motor
SynchronousReluctanceMotor
The PMassistance
SynchronousIPM Motor
Conclusions
Padova, 17 marzo 2017
N. Bianchi, M. Dai Prè, G. Grezzani, and S.Bolognani,“Design Considerations on Fractional–Slot Fault–Tolerant Synchronous Motors,”IEEE Trans. on Industry Applications, vol. 42, no. 4, pp. 997–1006, 2006.
M. Barcaro, N. Bianchi, and F. Magnussen,“Analysis and Tests of a Dual Three-Phase 12-Slot 10-Pole Permanent-Magnet Motor,”IEEE Transactions on Industry Applications, vol. 46, no. 6, pp. 2355–2362, Nov./Dec. 2010.
M. Barcaro and N. Bianchi,“Torque Ripple Reduction in Fractional-Slot Interior PM Machines Optimizing the Flux-BarrierGeometries,”International Conference on Electrical Machines (ICEM), 2012, Sept. 2012.
L. Alberti, M. Barcaro, and N. Bianchi“Design of a Low Torque Ripple Fractional-slot Interior Permanent Magnet Motor.”Conf. Rec. of the 2012 IEEE Energy Conversion Conference and Exposition, ECCE, Raleigh NC, USA,vol. 1, pp. 1–8, 2012.
L. Alberti and N. Bianchi,“Theory and design of fractional-slot multilayer windings,”Energy Conversion Congress and Exposition (ECCE), 2011 IEEE, Sept. 2011, pp. 3112 –3119.
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